Helicobacter pylori infection increases the risk of dyslipidemia in Chinese diabetic Population: a retrospective cross-sectional study

Background In contemporary times, increased prevalence of Helicobacter pylori (H. pylori) infection and elevated dyslipidemia levels present substantial public health challenges. However, the relationship between H. pylori and dyslipidemia remains inconclusive. No studies have yet conducted a population-based classification to investigate the impact of H. pylori infection on dyslipidemia in individuals with diabetes. Methods A retrospective cohort study was carried out on a total of 60,535 individuals who underwent health check-ups at the Health Examination Center in Taizhou Hospital from 2017 to 2022. Physical measurements, hematological markers and detection of H. pylori were gathered from all patients. The study population was further stratified into diabetic and non-diabetic groups for analysis. Results H. pylori infection was found to be an autonomous risk factor for dyslipidemia based on the results of multivariate logistic regression analysis (OR = 1.13, 95% CI: 1.03–1.24). However, no notable effect on dyslipidemia in the non-diabetic group was observed. Furthermore, at the follow-up, the group with persistent negative showed a significantly lower incidence ratio of dyslipidemia compared to the group with persistent infection (P = 0.006). The persistent negative group exhibited a significantly higher rate of improvement in dyslipidemia compared to the new infection group (P = 0.038). Conclusions In the diabetic population, the presence of H. pylori infection heightens the propensity for developing dyslipidemia. Therefore, the implementation of efficient eradication strategies for H. pylori infection could potentially lead to a decrease in the occurrence of dyslipidemia among individuals with diabetes.


Introduction
As one of the most pervasive chronic infectious diseases in humans, Helicobacter pylori (H.pylori) colonizes the gastric mucosa in around half of all adults [1][2][3][4][5].The majority of infections are acquired during early childhood and persist throughout an individual's lifetime [4][5][6].H. pylori not only serves as a primary contributor to clinical gastrointestinal disorders, such as stomach or duodenal ulcers and gastric cancer [3,4,7], but it is also linked to various extragastric conditions.Several independent studies have revealed associations between H. pylori infection and cardiovascular disease (CVD), type 2 diabetes mellitus (T2DM), as well as metabolic syndrome [8,9].
Dyslipidemia is a well-established independent risk factor for CVD, stroke, and atherosclerosis [10], characterized by increased concentrations of total triglycerides (TG), cholesterol (TC), low-density lipoprotein cholesterol cholesterol (LDL-c), or reduced high-density lipoprotein cholesterol (HDL-c) [11,12].In china, the prevalence of dyslipidemia exhibited a rapid increase from 2002 to 2015, while it is projected that annual CVD incidents will experience a surge of over 50% between 2010 and 2030 [12].Recently, numerous studies have unveiled the impact of dyslipidemia on the human microbiome.The microbiome plays an essential role in lipid metabolism within the human body [13][14][15], as it constitutes a complex and metabolically active ecosystem that is crucial for processing dietary components [15].A retrospective study, which included 5,077 Japanese patients, revealed a profound correlation between H. pylori infection and elevated LDL-c levels as well as reduced HDL-c levels among male patients [16].Similarly, another Korean cross-sectional analysis involving 37,263 participants showed the influence of H. pylori infection on dyslipidemia, including increased TC and LDL-c, and decreased HDL-c [17].In contrast to these findings, a study conducted on 58 patients showed that no notable alterations were observed in TC, TG, HDL-c or LDL-c levels subsequent to the eradication of H. pylori [18].Meanwhile, a meta-analysis did not find any significant correlation between H. pylori seropositivity and TC or TG levels [19].Thus, this ongoing controversy highlights the relationship.In addition, a systematic review study has unveiled the correlation between H. pylori infection and homeostasis model assessment IR (HOMA-IR), an indicator of insulin resistance (IR) which plays a crucial role in the pathogenesis of T2DM [20].Diabetes and dyslipidemia are interrelated metabolic disorders that reciprocally influence each other.However, no studies have been undertaken to explore the impact of H. pylori infection on dyslipidemia in individuals with diabetes as yet.
In this study, a retrospective cross-sectional survey and cohort investigation were carried out to elucidate the potential contribution of H. pylori infection to the risk of dyslipidemia in the Chinese diabetic population.Furthermore, a comprehensive analysis was performed to investigate the correlation between H. pylori infection and dyslipidemia in individuals with T2DM.

Sample population
Between January 2017 and September 2022, a cumulative number of 60,535 patients aged over 20 years underwent extensive health screening assessments at the Health Management Center of Taizhou Hospital in Zhejiang Province, China.The exclusions for invalid and missing data are as follows: (1) age below 18 years or above 80 years; (2) lack of comprehensive clinical data and personal history; (3) a history of malignancy, abnormal liver or kidney function, thyroid disease and severe obesity; (4) previous or current H. pylori eradication therapy and dyslipidemia therapy [21].Finally, 46,808 participants underwent a single physical examination, while 24,731 completed multiple physical examinations.Data from the initial examination were utilized for the cross-sectional analysis among individuals who underwent multiple examinations, as well as those who had only undergone one examination.For the cohort analysis, we specifically selected data from the initial and final health checkups with an interval time more than 12 months.This study has been granted ethical approval by the ethics committee at Taizhou Hospital (K20220790).

Clinical data collection
The proficient nurses at the Health center gathered and documented basic information, including age, gender, smoking habits, alcohol consumption, and personal medical history of the patients.Additionally, they also measured diastolic blood pressure (DBP) and systolic blood pressure (SBP) after a 5-minute period of rest in a calm seated position.After a 12-hour overnight fast, venous blood samples were collected from individuals in the morning on an empty stomach to measure laboratory serum biochemical parameters, including TG, TC, HDLc, LDL-c, uric acid, creatinine and glycated hemoglobin A1c (HbA1c).fasting blood glucose (FBG) was collected after an 8-hour fast.The calculation formula of BMI index was [weight/height squared (kg/m 2 )].

Definition of dyslipidemia and H. pylori infection
Dyslipidemia was defined as meeting any of the following criteria: TC levels ≥ 240 mg/dL, TG levels > 200 mg/dL, reduced HDL-c levels < 40 mg/dL for men and < 50 mg/ dL for women, or elevated LDL-c levels ≥ 130 mg/dL.The occurrence of dyslipidemia was determined based on the manifestation of either "borderline high LDL-c" or "low HDL-c, " whichever occurred first [11].The methodology used for detecting H. pylori was the 13 C/ 14 C-urea breath test ( 13 C/ 14 C-UBT).The specific steps of the 13 C-UBT were as follows: (1).Collect the initial breath sample after fasting for 3 h; (2).Take a 13 C urea capsule and wait for 30 min; (3).Exhale into the special gas colloection bag again; (4).Analyze the results on the instrument.The specific steps of the 14 C-UBT were as follows: (1).Swallow a 14 C urea capsule with warm water; (2).Wait for 15 min; (3).Continuously exhale into the gas collection bag for 1-3 min; (4).Insert the bag into the detector for analysis [22].

Definition of H. Pylori status
Studied participants were classified into four groups: persistent infection group ( H. pylori status at the baseline and endpoint positive), eradication infection group (H.pylori positive at the first visit, with H. pylori negative at the endpoint), persistent negative group (baseline and endpoint H. pylori status negative) and New infection group (H.pylori negative at the baseline, with H. pylori positive at the endpoint).Endpoints were defined as the time of the second or more physical examinations in which dyslipidemia was developed and, if dyslipidemia was not developed persistently, the time of the latest follow up between January, 2017 and September, 2022.

Statistical analysis
In this study, continuous and categorical variables were presented as mean ± standarddeviation (SD) and counts or percentages, using Student's t test or one-way ANOVA and chi-square test for comparisons between the risk groups and the subgroups, respectively.Multivariate logistic regression models were used to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for dyslipidemia associated with H. pylori infection, while controlling for potential confounding factors.Four adjustment models were fitted for other risk factors.All statistical analyses were performed using R version 4.1.3,and variables with a P-value less than 0.05 were considered statistically significant.

Part I Baseline demographic characteristics
The baseline characteristics of all enrolled participants are shown in Table 1.Out of a total of 60,535 individuals who underwent physical examinations, 37,286 (61.6%) were male and 23,249 (38.4%) were female.The infection rate of H. pylori was 37.0%.Among those who are positive for the H. pylori infection, there is a higher proportion of males, 62.7% vs. 60.9%.Compared to the negative group, individuals with diabetes had a higher rate of H. pylori infection, 15.1% vs. 14.4% (P = 0.02).However, there was no statistical difference between dyslipidemia and H. pylori infection, 37.0% vs. 36.2%(P = 0.069).
To further explore the potential link between H. pylori infection and the development of dyslipidemia in diverse populations, a subgroup analysis was performed using univariate analysis to examine the risk factors influencing dyslipidemia in both diabetic and non-diabetic individuals.The basic characteristics of dyslipidemia patients in the non-diabetic and diabetic groups are presented in Table 2.In the non-diabetic group, individuals with dyslipidemia exhibited a significant elevation in TG levels  In the diabetic group, univariate logistic regression models showed that H. pylori infection was associated with a higher risk of dyslipidemia (OR = 1.13, 95%CI: 1.03-1.24),as illustrated in Fig. 2. Furthermore, gender, age, hypertension, BMI, and HbA1c were identified as independent risk factors for dyslipidemia (P < 0.05).Four models with progressive degrees of adjustment were fitted for potential confounders.In addition to gender and age, adjustments were made for hypertension, HbA1c, smoking, and alcohol consumption.The presence of H. pylori infection remains a risk factor for dyslipidemia, as shown in Table 3.

Part I Correlation between H. Pylori infection status and dyslipidemia
Among the 1633 patients with diabetes, a total of 1477 individuals underwent follow-up for more than one year.Out of these, 358 (24.2%) patients did not have dyslipidemia during their initial physical examination.The incidence rates of dyslipidemia were 44.1% and 64.3% in the persistent negative and positive groups, respectively.Additionally, the eradicated infection group had a rate of 69.6%, while the new infection group had a rate of 67.7%.The persistent negative group exhibited a significantly lower incidence ratio of dyslipidemia compared to that in the persistent infection group (P = 0.006), as depicted in Fig. 3A.
Out of the 1,477 patients with diabetes, 1,119 (75.8%) individuals had dyslipidemia during their first visit.The improvement rates for dyslipidemia were 22.6%, 18.3%, 19.7%, and 13.6% in the persistent negative, persistent positive, eradicated infection, and new infection groups respectively.The new infection group exhibited a significantly diminished rate of improvement in dyslipidemia compared to the persistently negative group (P = 0.038).In addition, the rate in the persistent positive group was found to be lower than that observed in both the persistent negative and eradication groups; however, this  difference did not reach statistical significance, as shown in Fig. 3B, C, D.

Discussion
The correlation between H. pylori infection and dyslipidemia remains a topic of controversy due to the lack of studies that stratify populations based on diabetes status, which is necessary for accounting potential confounding effects when assessing the impact of H. pylori infection on dyslipidemia.The association between H. pylori infection and dyslipidemia has been validated in this study, which was conducted on a large sample population.Nevertheless, considering the distinctive characteristics of IR and hereditary vulnerability in diabetic individuals compared to non-diabetic individuals, it is crucial to investigate the variations in the impact of H. pylori infection on dyslipidemia.
This large cross-sectional research has undertaken a separate analysis of the association between H. pylori infection and dyslipidemia, with a specific focus on patients with diabetes mellitus.The prevalence of H. pylori infection was found to be higher in the dyslipidemia group compared to the non-dyslipidemia group, indicating a positive correlation between H. pylori infection and dyslipidemia.Furthermore, even after adjusting for multiple confounding variables, H. pylori infection remains a significant independent risk factor for the progression of dyslipidemia.At the same time, we observed that dyslipidemia was more common in females and populations with higher levels of FBG, uric acid, or BMI.Indeed, these aforementioned factors were also independent risk factors for dyslipidemia.This means that these people are vulnerable to H. pylori infection.In addition, the further cohort study revealed a significantly higher incidence of dyslipidemia in the persistent infection group compared to the persistent negative group, while the rate of improvement in dyslipidemia was notably lower in the new infection group than that observed in the persistent negative group.These pieces of evidence suggested that H. pylori infection may potentially contribute to the occurrence and progression of dyslipidemia.It was consistent with a large cohort study conducted by Park, Y., et al [11].This implies that eradicating H. pylori infection within diabetic individuals may have favorable implications in terms of mitigating the incidence of dyslipidemia.Therefore, internists should carefully consider the increased risk of dyslipidemia in patients with H. pylori and advocate for eradication therapy, especially in individuals with diabetes.
The pathogenesis of dyslipidemia can be ascribed to a blend of hereditary, ecological, and metabolic elements [23].Several studies have indicated a potential correlation between dyslipidemia and H. pylori infection, further emphasizing the multifactorial nature of this condition [11,24].Recent evidence has demonstrated that H. pylori infection induces the upregulation of various inflammatory mediators, including macrophages, tumor necrosis factors (TNF), and several interleukins.The release of macrophages and interleukins results in the accumulation of active substances, exacerbating oxidative stress reactions in the body and promoting accelerated mobilization of fat [25].TNF-α impedes the activity of lipoprotein lipase, facilitating lipid mobilization in tissues and consequently inducing perturbations in lipid and lipoprotein metabolism [26][27][28].Additionally, Other studies have shown that diabetic patients may have a higher risk of developing Non-alcoholic fatty liver disease (NAFLD) due to H. pylori infection, and there is a non-linear relationship between H. pylori infection and HbA1c.This could be attributed to the fact that both dyslipidemia and NAFLD are metabolic-related diseases, and H. pylori infection leads to increased IR as well as changes in lipid and lipoprotein metabolism [29][30][31][32].The infection may worsen damage to pancreatic cells, aggravating insufficient insulin secretion and leading to abnormal hormone secretion in mucosal inflammation [33][34][35].This could potentially explain the increased occurrence of dyslipidemia among H. pylori-positive individuals within the diabetic population as observed in this study.
The strengths of this research lie in the implementation of a cross-sectional design, a comparatively large sample size, population categorization, and the inclusion of a cohort to evaluate the impact of current infection and its eradication on lipid profiles, which enables us to determine the causal relationship accurately.The outcomes of this study have confirmed a positive correlation between dyslipidemia and H. pylori infection in diabetic patients, and persistent H. pylori infection increases the risk of developing dyslipidemia.To our knowledge, this study represents a pioneering investigation into the potential impact of H. pylori infection on dyslipidemia within a substantial diabetic population.Nonetheless, it is imperative to acknowledge that certain limitations were also evident in this study.First of all, the inherent constraints of retrospective research design should be recognized.Second, this study is limited to a single center, which implies certain constraints.To establish more reliable evidence, it may be necessary to conduct multicenter and longitudinal studies.Third, this study focuses on diabetic populations who have undergone regular health check-ups; therefore, caution should be exercised when extrapolating these findings to broader populations.In addition, the H. pylori infection status was exclusively determined through the 13 C/ 14 C-UBT, without resorting to gastroscopy biopsy or microbial culture for diagnosing H. pylori infection.Since other urease-producing bacteria were found in the stomach, this could lead to a false positive result for H. pylori infection in the urea test.There are many alternative non-invasive diagnostic techniques available for diagnosing H. pylori infection, such as serological testing for anti-H.pylori antibodies, the stool antigen test (SAT), and the direct detection of H. pylori genetic material in stool via PCR.Nevertheless, previous studies have shown a robust concordance between the 13 C/ 14 C-UBT and gastroscopy biopsy [36], implying that the 13 C/ 14 C-UBT displays exceptional diagnostic accuracy and commendable performance [3,37,38].Finally, despite the comprehensive inclusion of significant confounding variables in the multivariable analysis, the potential existence of residual confounders due to measurement errors or insufficient measurements that cannot be entirely ruled out.

Conclusion
H. pylori infection is identified as an autonomous risk factor for dyslipidemia in the diabetic population.Furthermore, prolonged H. pylori infection may augment the likelihood of developing dyslipidemia.Consequently, eradicating H. pylori infection among individuals with diabetes could potentially contribute to a reduction in the incidence of dyslipidemia.

( 2 .
35 ± 2.02 vs. 1.05 ± 0.32) and LDL-c levels (2.99 ± 0.76 vs. 2.29 ± 0.43).However, there was no significant correlation between H. pylori infection and dyslipidemia (P = 0.82) among the non-diabetic group.Moreover, significant statistical differences were observed in age, gender, FBG, BP, lipid parameters, and H. pylori infection (P = 0.012) between dyslipidemia subjects within the diabetic group and non-dyslipidemia subjects.The heterogeneity in H. pylori infection among diverse populations of patients with dyslipidemia is depicted in Fig.1.

Fig. 3 Fig. 2
Fig. 3 Effect of different Helicobacter pylori infection statuses on the development of dyslipidemia: (A) Comparison between the persistent infection group and the persistent negative group.Effect of different Helicobacter pylori infection statuses on the improvement of dyslipidemia: (B) Comparison between the persistent negative group and the new infection group.(C) Comparison between the persistent negative group and the persistent infection group.(D) Comparison between the eradicated infection group and the persistent infection group AbbreviationsH.pylori Helicobacter pylori CVD Cardiovascular disease T2DM Type 2 diabetes mellitus TG Total triglycerides TC Total cholesterol HDL-c High-density lipoprotein cholesterol LDL-c Low-density lipoprotein cholesterol IR Indicator of insulin resistance HbA1c glycated Hemoglobin A1c TNF Tumor necrosis factor 13 C/ 14 C-UBT

Table 1
Baseline characteristics of the entire physical examination cohorts

Table 2
Baseline characteristics of dyslipidemia population in the non-diabetic and diabetic group